The present invention relates in general to priming pumps that are part of fluid systems constructed and arranged to draw in fluid from a supply and deliver the fluid to a downstream site. More specifically, the present invention relates to the use of a valve arrangement to manage and control the flow of fluid through the priming pump. The valve arrangement of the present invention includes a first valving portion on the intake side of the priming pump and a second and cooperating valving portion on the outlet (i.e., delivery) side of the priming pump.
While the present invention is disclosed in the context of a priming pump, some earlier valve designs are used for related fluid pumps, such as the valve plate assembly disclosed in U.S. Pat. No. 4,776,776, issued Oct. 11, 1988 to Jones. The '776 patent is directed to a valve plate assembly for use in small reciprocating piston pumps such as small air compressors used for medical purposes. The '776 patent also includes a background description that covers some of the earlier valve designs and some of the problems associated with those earlier valve designs. For example, one of these earlier valve designs is described in the '776 patent as including a valve plate containing inlet and outlet ports that is mechanically clamped between a cylinder and a cylinder head. As described, valve reeds are riveted or otherwise attached to opposite sides of the valve plate to form check valves which allow air to flow through the inlet port into the cylinder during intake or suction stroke of the piston and to flow through the outlet port during the compression stroke.
As described in the '776 patent, problems are often encountered during manufacture of compressors having reed valves. The prior art valve plate assemblies are relatively expensive to manufacture and tend to leak, which as a consequence reduces the output from the compressor. The metal valve reeds are subject to bending during assembly handling. Therefore, it is necessary to test each compressor after it is assembled and it often is necessary to partially dismantle a newly manufactured compressor to replace a faulty valve plate assembly.
Further, the '776 patent describes the prior art as disclosing valve plate assemblies in which a flat resilient member is clamped over ports. Circular or somewhat parabolic-shaped flaps are cut in the resilient member to form valves attached to the member by resilient hinges. The valves are positioned to cover the ports. This arrangement eliminates some of the problems with reed valves. However, closing of the valve flaps is limited by the limited force exerted by the resilient hinge. Also, additional components, such as a second rigid plate, are required to form both intake and exhaust valves.
The '776 invention is described as being directed to a valve plate assembly for use in small reciprocating piston fluid pumps such as low capacity air compressors. The assembly has a valve plate similar to the prior art valve plate having openings which define inlet and outlet ports. A rubber valve molding is wrapped around the edge of the valve plate to form a seal between the valve plate and the cylinder head. The valve molding has an integral first flap which covers the inlet port opening only on the cylinder side of the valve plate to form an intake check valve and has an integral second flap which covers the outlet port opening only on the cylinder head side of the valve plate to form an outlet check valve.
Another reference of interest for its description of a reed valve assembly is U.S. Pat. No. 4,437,490, issued Mar. 30, 1984 to Demers, et al. The disclosed reed valve assembly includes a reed sandwiched between two base members, such as a valve plate and a cylinder head of a compressor. The reed is clamped between the two members at a central part whereby both free ends of the reed can flex. The base members are so structured that one free end of the reed forms an intake valve member and the other a discharge valve member, whereby a single reed serves both as an intake valve member and as a discharge valve member. The Demers, et al. structure is noticeably different from the present invention in that the single reed must be clamped between two separate components and those two separate components must in turn be joined together by the use of threaded fasteners. Not only is there added size and cost with the Demers, et al. design, but there is the potential for the clamping force to weaken and the reed to loosen or shift position. The integrally molded combination of the present invention and the unitarily molded design of the second embodiment offer improvements to the Demers, et al. design.
While there are other earlier patent references that disclose pump designs and other earlier patent references that disclose cooperating valve assemblies, the '776 and '490 patents should provide a good, basic understanding of how fluid pump valves can be constructed and assembled and how they function.
Since the present invention is disclosed in the context of a priming pump, it should be noted that the priming pumps used today as part of fluid systems employ several different schemes of controlling pump valve action. Each of these different schemes typically require several components to accomplish the task of controlling the valve action at the fluid inlet and the valve action at the fluid outlet (i.e., discharge). As an improvement to these more complicated designs, the present invention focuses on simplicity and a minimal number of parts. As will be described in greater detail, the present invention is configured with a reed valve molded into a carrier device or substrate, without the use of any additional components, connecting hardware, etc. The present invention does not involve any mechanical components, fasteners, or devices to secure the reed valve and valve body or substrate together. The assembled state is achieved by the molding process. The valving system of the present invention works on the pump actions that draw fluid through one valve portion and exhausts it out through the other valve portion. The concept of having no additional parts makes the design of the present invention smaller, more efficient and less expensive compared to other designs in terms of component part reduction and labor cost.